> How about the trivial solution below?
> 
> Add this somewhere widely included:
> i.e. src/sys/arch/mips/include/cdefs.h
> 
> #if defined(__mipseb__) || defined(__mipsel_)
> #define __mips__ 1
> #endif

Unfortunetely, this doesn't resolve the problems of makefiles.
(e.g. MACHINE_ARCH vs ARCHSUBDIR hack in many makefiles.)

About xlint problem, adding 
	-DMACHINE_SRCARCH=${MACHINE_ARCH:C/mipse[bl]/mips/}
and using it might be cleaner way for the short term.
Making MACHINE_SRCARCH global is what I think in long term.

Perhaps, another way is reverting changes of
"MACHINE_ARCH=mips -> MACHINE_ARCH=mipseb/mipsel" and adding new
varible "MACHINE_BINARCH=mipseb/mipsel". The reason I like this way is
"ARCH" reminds me instruction set architecture and "arch/XXX" source
directory name. But this must cause BIG pain, because Todd made great
effort to convert mips -> mipsel/mipseb....
--
soda